In situ exploration of large dynamic networks

The analysis of large dynamic networks poses a challenge in many fields, ranging from large bot-nets to social networks. As dynamic networks exhibit different characteristics, e.g., being of sparse or dense structure, or having a continuous or discrete time line, a variety of visualization techniques have been specifically designed to handle these different aspects of network structure and time. This wide range of existing techniques is well justified, as rarely a single visualization is suitable to cover the entire visual analysis. Instead, visual representations are often switched in the course of the exploration of dynamic graphs as the focus of analysis shifts between the temporal and the structural aspects of the data. To support such a switching in a seamless and intuitive manner, we introduce the concept of in situ visualization--a novel strategy that tightly integrates existing visualization techniques for dynamic networks. It does so by allowing the user to interactively select in a base visualization a region for which a different visualization technique is then applied and embedded in the selection made. This permits to change the way a locally selected group of data items, such as nodes or time points, are shown--right in the place where they are positioned, thus supporting the user's overall mental map. Using this approach, a user can switch seamlessly between different visual representations to adapt a region of a base visualization to the specifics of the data within it or to the current analysis focus. This paper presents and discusses the in situ visualization strategy and its implications for dynamic graph visualization. Furthermore, it illustrates its usefulness by employing it for the visual exploration of dynamic networks from two different fields: model versioning and wireless mesh networks.     

DelosDLMS

DelosDLMS is a novel digital library management system (DLMS) that has been developed as an integration effort within the DELOS Network of Excellence, a European Commission initiative funded under its fifth and sixth framework programs. In this paper, we describe DelosDLMS that takes into account the recommendations of several activities that were initiated by DELOS including the DELOS vision for digital libraries (DLs). A key aspect of DelosDLMS is its novel generic infrastructure that allows the generation of digital library systems out of a set of basic system services and DL services in a modular and extensible way. DL services like feature extraction, visualization, intelligent browsing, media-type-specific indexing, support for multilinguality, relevance feedback and many others can easily be incorporated or replaced. A further key aspect of DelosDLMS is its robustness against failures and its scalability for large collections and many parallel user requests. We discuss the current status of an effort to build DelosDLMS, a Digital Library Management System that integrates in various ways several components developed by DELOS members and showcases a great variety of functionality that is outlined as part of the DELOS vision.     

Produktgetriebene Entwicklung von Softwareproduktlinien

For the realization of software product families the software-technical concept of the software product line finds an increasing spreading. Due to the high initial costs of current methods for software product line development these methods are not suitable for small and medium-size software enterprises. The contribution of this paper is a method for software product line development which reduces costs for the establishment of a software product line, supports a product-driven advancement of product lines and enables the application of the product line approach in small and medium-size software enterprises. After an introduction to the state of the art, we analyze the requirements for the development of software product lines in small and medium-size enterprises. Subsequently, a product-driven development method is introduced which considers these requirements and supports an evolutionary development of software product lines.     

Constructing and visualizing chemical reaction networks from pi-calculus models

The π-calculus, in particular its stochastic version the stochastic π-calculus, is a common modeling formalism to concisely describe the chemical reactions occurring in biochemical systems. However, it remains largely unexplored how to transform a biochemical model expressed in the stochastic π-calculus back into a set of meaningful reactions. To this end, we present a two step approach of first translating model states to reaction sets and then visualizing sequences of reaction sets, which are obtained from state trajectories, in terms of reaction networks. Our translation from model states to reaction sets is formally defined and shown to be correct, in the sense that it reflects the states and transitions as they are derived from the continuous time Markov chain-semantics of the stochastic π-calculus. Our visualization concept combines high level measures of network complexity with interactive, table-based network visualizations. It directly reflects the structures introduced in the first step and allows modelers to explore the resulting simulation traces by providing both: an overview of a network’s evolution and a detail inspection on demand.     

Model-driven design for the visual analysis of heterogeneous data

As heterogeneous data from different sources are being increasingly linked, it becomes difficult for users to understand how the data are connected, to identify what means are suitable to analyze a given data set, or to find out how to proceed for a given analysis task. We target this challenge with a new model-driven design process that effectively codesigns aspects of data, view, analytics, and tasks. We achieve this by using the workflow of the analysis task as a trajectory through data, interactive views, and analytical processes. The benefits for the analysis session go well beyond the pure selection of appropriate data sets and range from providing orientation or even guidance along a preferred analysis path to a potential overall speedup, allowing data to be fetched ahead of time. We illustrate the design process for a biomedical use case that aims at determining a treatment plan for cancer patients from the visual analysis of a large, heterogeneous clinical data pool. As an example for how to apply the comprehensive design approach, we present Stack'n'flip, a sample implementation which tightly integrates visualizations of the actual data with a map of available data sets, views, and tasks, thus capturing and communicating the analytical workflow through the required data sets.     

Energieinformatik

Due to the increasing importance of producing and consuming energy more sustainably, Energy Informatics (EI) has evolved into a thriving research area within the CS/IS community. The article attempts to characterize this young and highly dynamic field of research by describing current EI research topics and methods and provides an outlook of how the field might evolve in the future. It is shown that two general research questions have received the most attention so far and are likely to dominate the EI research agenda in the coming years: How to leverage information and communication technology (ICT) to (1) improve energy efficiency, and (2) to integrate decentralized renewable energy sources into the power grid. Selected EI streams are reviewed, highlighting how the respective research questions are broken down into specific research projects and how EI researchers have made contributions based on their individual academic background.     

Holonic transport scheduling with teletruck

TELETRUCK is a multiagent-based dispatch support system developed in close collaboration with forwarders and transport engineers. The system supports dispatch officers in route planning, fleet management, and driver scheduling. TELETRUCK allows for dynamic planning and online optimization of transport orders based on an integration with modern telecommunication facilities. The TELETRUCK approach uses holonic agents, i.e., agents composed of subagents that act in a corporated way, in order to achieve a flexible, structured resource management in the planning process. A brief overview is given of the current implementation status of the TELETRUCK application prototype. Communication, coordination, and resource control distinguishing holonic from common multiagent systems are discussed. The underlying algorithms and protocols are described. Future extensions of the approach for intermodal and intercompany transport planning are discussed aiming at a smooth integration of modern transport and telecommunication networks.     

Opening the AC-unification race

This note reports about the implementation of AC-unification algorithms, based on the variable-abstraction method of Stickel and on the constant-abstraction method of Livesey, Siekmann, and Herold. We give a set of 105 benchmark examples and compare execution times for implementations of the two approaches. This documents for other researchers what we consider to be the state-of-the-art performance for elementary AC-unification problems.